The present invention relates to presses and preferably to gap frame hydraulic presses formed from modular parts.
Machines that are used to form, trim, blank and perforate metal sheets, strips, bars etc. are commonly called punch presses. Punch presses are manufactured in various configurations best suited for the particular product it is to produce. The main frame work of most punch presses is made of iron castings or steel plates joined together by welding and are called fabrications or weldments.
Pound for pound steel is much stronger that iron especially when subject to stretching or bending forces. Thus, a fabricated steel press of the same capacity as an iron press would weigh considerably less than a press made from iron castings.
The actual labor cost to manufacture a punch press from iron castings is a great deal less than the labor required to produce weldments, heat treat, and finish machine a steel press. This is due to the fact that the iron is cast to the final net shape of components and only needs to be finish machined on mating surfaces.
In order to produce an iron casting, it is necessary to manufacture a pattern of the same shape from suitable material. Once a pattern is made it can be used over and over again to produce that particular casting. These patterns are very costly and unless they can be used a certain minimum number of times it would be more economical to manufacture the press from steel weldments.
In the case of castings for punch presses the pattern is implanted in sand then removed and molten iron is poured into the cavity formed by the pattern. Intricate shapes are produced by this process. Steel can also be cast by this process and would be superior to iron for this purpose, but, molten steel is much more difficult to cast into intricate shapes than molten iron because molten iron pours like water and molten steel pours like syrup. Also, molten steel breaks down the sand mold much more than molten iron especially in the upper portion of the sand mold, this causes the molten steel to mix with the sand in these areas and reduces the quality of the material in the areas wherever the molten steel mixed with the sand. Cast steel is also much more difficult and costly to machine than cast iron.
The above disadvantages with cast steel are greatly reduced if the design of the product is simple such as the design of the present invention. Because of its simple shape, the cast steel components of the present invention can be successfully cast without dilution with sand and the pattern cost is very low.
In certain types of presses, iron is generally unsuitable as a construction material. One of these types is the "C" frame press also called a "gap frame press". The gap frame press is indispensable for certain operations. It differs from most press designs because it has to resist the forces acting on it by means of a cantilever type of construction. These forces are much the same as those acting on the common "C" clamp, which if made of brittle cast iron would break much easier than the same clamp made of steel.
The present invention combines the economy of cast iron construction with the strength of steel due to the design of the channels used as cantilever beams. These channels are able to be cast of steel because the simplicity of their shape enables them to be cast without breaking down the upper part of the mold and mixing the molten steel with the sand. In this way, consistent physical properties are attained in the beams from casting to casting. Also, the simplicity of the channel shaped cross section of the beams enables patterns to be made at very low cost.
The invention also provides a means to vary the bed height, the height of the die space and the width of the press at reasonable cost by means of modular construction techniques. The invention also provides a C-shaped frame with an open back as well as a guided ram assembly.
From the following detailed description, subjoined claims and drawings, other objects and advantages of the present invention will become apparent to those skilled in the art.